Aged individuals and astronauts experience bone loss despite rigorous physical activity.
Bone mechanoresponse is in part regulated by mesenchymal stem cells (MSCs). We reported that
daily low intensity vibration (LIV) restores MSC proliferation in senescence and simulated
microgravity models, suggesting reduced mechanical signal delivery to MSCs likely contributes
to declining bone mechanoresponse. To this end, we have developed a 3D bone marrow analog which
controls trabecular geometry, marrow mechanics and external stimuli.
Finite element (FE) models of hydrogels, representing bone marrow, were generated using
instantaneous compression (1000% strain/s, 20% strain) and relaxation experiments (100s) of
both gelatin and hyaluronin-based hydrogels. Experimental and in silico vibration experiments
using molded-gelatin wells (widths= 4 , 5, 6 and 8 mm) were performed under 1g acceleration,
100 Hz for FE model calibration.
For MSC experiments, 0.25cmgyroid-based trabeculae of bone volume fractions (BV/TV)
corresponding to adult (25%) and aged (13%) mice were printed using polylactic acid. MSCs
encapsulated (1x106 cells/mL) in migration-permissive hydrogelswithin [sic] printed trabeculae
were exposed to LIV (1g, 100 Hz, 1 hour/day). After 14 days, type-I collagen, Ki-67, f-actin
(n=3/grp) were quantified for extracellular matrix composition, proliferation, and morphology
and grouped with respect to the maximum von Mises strain for 13.5% and 25% BV/TV scaffolds using
the calibrated FE models.